Seperating Deck from Hull

Discussion in 'Boatbuilding' started by phil32, Jun 20, 2011.

  1. phil32
    Joined: Jun 2011
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    phil32 Junior Member

    Gentlemen
    I have a 11 foot, probably 30 yrs old fiberglass Dingy, I want to restore for my daughter. I would like some help in seperating the deck from the hull in order to replace the water saturated foam. I have removed the rub rail and dont know exactly how to proceed without tearing anything up. Any help would be much appreciated.
    Thank you
    Best regards
    Phil
     

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  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Remove all the flange screws, which are usually under the rub rail and all other hardware that might be screwed to a pad on the hull shell. Take a putty knife and heat it with a torch, then slide it along the seam until you've pushed through. Insert a wooden wedge and force the cap up a little, using the hot knife or a utility knife with a sharp blade, work down the seam, cutting sealant and adding more wedges as you go. Eventually, you'll "talk it into it" and it'll become obvious what you need to do next.
     
  3. phil32
    Joined: Jun 2011
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    phil32 Junior Member

    Par
    Thank you very much for the information, I just was not sure how it was put together but your explanation solves a lot of mysterys. I assume once you pry the sides up and wedge as you go it should release and be able to remove. again thank you for taking the time to help us.
    Phil
     
  4. PAR
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    PAR Yacht Designer/Builder

    Usually, you have to cut through the "bedding compound" which will be butyl rubber or a more modern polyurethane sealant. Both can be cut or sue the hot knife trick. The wedges help provide access to the next bit of exposed bedding compound as you work your way around the flange. AT some point, the bedding compound will not be able to withstand the continuous upward pull of the cap (wedges and your insistence) and it'll start to tear the bedding, which is the sign you're about done.
     
  5. phil32
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    phil32 Junior Member

    Par,.
    This seems to be working however i cannot get it lose from the transom
    any suggestion.
    Thanks
    Phil
     

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  6. PAR
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    PAR Yacht Designer/Builder

    That transom is very probably bonded to the deck cap, because of the expectation of an outboard. Considering it's age, the transom is very probably shot and needs to be replaced anyway.

    This coupled with the "shoe box" style of flange, makes things more difficult. Often you can take a saws-all (reciprocating saw), break off a metal cutting blade so it's not any deeper (at full stroke) then the transom is thick and work around the perimeter, where the transom meets the hull shell. Usually the shoe box style of joint, changes at the transom and it's just an overlapping sort of joint. You can work the saw blade along this joint and cut the top bond. The inside face of the deck cap will still be bonded to the transom core (plywood), but I'm betting it's good and rotten and it'll just peel right off, once you tip up the forward potion of the deck cap.

    I don't try to lift the cap uniformly, but rather use the leverage available with the cap to yank it off. By this I mean I lift the forward section, to create a "shearing" action along the flange, which often will break the bond (bits of flange too). Lifting it straight up means you're fighting everything, gravity, bond line, a forgotten fastener or two, the transom bond, etc. Lift the front and block it up with 2x4's. At this point (assuming by the photos) you should just about be able to climb in the forward half if it was raised up. Lastly, by raising the forward portion continuously, as you work aft along the flange, you'll tear the transom core bond from bottom to top, which is a lot easier to do. If you try to lift straight up (which it appears you are in the photos) the transom core bond is fully working against you, because it's not being peeled. Think of the transom bond as removing a bandaid. If you try to lift it off, all points at once, it's very difficult, but if you start at one end and peel, she'll come off a lot easier.

    One final point is you're going to do some damage as you've probably surmised by now. It's the nature of the beast. Sometimes it's necessary to cut a part of the deck cap/liner. Yea, this sucks, but a cut line can be of your choosing and is much easier to repair then a section of broken laminate. If you have to cut, use the saws-all again about 6" forward of where the deck cap/liner will meet the transom. Cut just through the liner naturally. Once you've freed the liner, you can peel the inner face of the tranom off, preserving the inside corners, which provides a lot of stiffness to the liner. The one thing you don't want to do is cut down through the curved corners. Fairing this up is much harder then the relatively flat areas just forward of these corners, plus it's just a laminate repair, rather then a full blown laminate build up (if you cut the corners). Another obvious cut location is about 6" inboard of these same corners, but into the transom core. You can do this with an angle grinder, router, laminate trimmer, circular saw. This is actually a better idea as the corners are preserved and the flat section left on the transom can be easily knocked off with a chisel and some inventive cursing.
     
  7. phil32
    Joined: Jun 2011
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    phil32 Junior Member

    Par.
    Once again thank you for all your expertise. First the tramsom is solid and we are not looking to mount anything bigger than a trolling motor. Second my goal is to remove the water soaked foam and replace it.

    Giving your instructions at starting the lift from the front would it be possible to lift it high enough to remove some if not all the foam and keep the transom bond in tact.
    Fathers with little skills trying to pass on something to your daughter often get us in trouble. The old boat is probably not worth much totally refurbished but she is so attached to it, its worth the struggle.
    Again thank you for taking the time to help us
    Best regards
    Phil
     
  8. PAR
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    PAR Yacht Designer/Builder

    I use an engine hoist or chain fall for this size boat Phil. I find or make a strong attachment at the bow, hook on and the let the weight of the hull shell preform much of my work for me. Sometimes on a really light boat, like yours, I'll racket strap the hull shell down to her trailer, once I have some separation.

    Yes, you can remove some of the foam, with the shell pried up. It's more difficult of course, compared to removing the deck cap, but a doable thing. Having been in your precise situation, I understand the effort and project requirements (mine got attached to some ugly stuff too). I'm not sure how far aft you'll be able to reach to remove foam, but give it a shot and see where you land.
     
  9. phil32
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    phil32 Junior Member

    Par
    Do you think it might be better to cut out access holes or a pretty good size hole 3'x3' in the deck for access and then replace with plywood and glass over it. I dont know exactly how to do that but im not having any luck getting the hull seperated and doing a lot of damage to the flange
    Phil
     
  10. CutOnce

    CutOnce Previous Member

    Many inspection ports miraculously end up on the damaged part of surfaces. Using an inspection port to replace a damaged area is a time honored tradition in low cost dinghy repair.

    --
    CutOnce
     
  11. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    What are you lifting the hull with? Wedges just get you started, you should change to a real lifting device, once you can strap a 2x4 under the forward portions. An engine hoist, a come-a-long from a tree branch, some well fed friends, can exert force at the forward end, while you use a pair of wedges to "keep what you gain", as it's lifted.

    If you reach a point where it doesn't want to come off, there's usually a reason. Something wasn't removed, a hidden screw or the dreaded bonded liner. The liner can become bonded, intentionally or unintentionally by the crew that built it. It's imposable to identify this until you get the cap off.

    Access holes work, though not knowing where the foam is and having limited access through a "new hatch" can be as bad as what you're experiencing.

    Again not being able to see what you're trying or the areas of the hull that seem to be causing troubles leaves me in a hole as far as additional advice. In the end, you need to get the foam out. If the deck cap thing has got you beaten, then maybe the big 'ol hatch trick can work for you.
     

  12. phil32
    Joined: Jun 2011
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    phil32 Junior Member

    Par
    We did the access thru the deck and surprisingly we are able to get to and remove most of the foam and its comeing up fairly easy . One thing we ran into is about half way toward the stern we ran into a different type and color of foam (white) its in between the hull and the brown foam. Do you know if this factory or some type later repair?
    Again thanks for your help.
    Phil
     

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